The use of a molluscicide in conjunction with chemotherapy to control Schistosoma haematobium at the Barombi Lake foci in Cameroon. III. Conclusions and costs.

Although Frescon successfully controlled snails on the margins of the Barombi lakes, and although the continuation of niridazole and Frescon control reduced transmission of S. haematobium very considerably, practical difficulties, which are discussed, rendered the twin goals of snail- and parasite-eradication impossible to achieve. The "break-point" in transmission of S. haematobium appears to lie so low as to be practically synonymous with total eradication. Control operations would thus have had to be maintained indefinitely in order to avoid a rapid return to the pre-control situation. The cost of the control element in this combined chemotherapeutic and molluscicidal research project, at 2 lacustrine foci of S. haematobium transmission in the United Republic of Cameroon, was 9 to 10 U.S. dollars per year per head of population protected. This sum is about three times the country's total estimated expenditure per head of population on all health and social services for the year 1974-1975. The high cost of such operations is only likely to be acceptable where schistosomiasis causes much ill-health and reduced economic productivity, and where tangible benefits may be expected from a reduction in the intensity of infections, short of eradication.